"""Application settings (environment variables, .env)."""

from __future__ import annotations

import os
from functools import lru_cache
from pathlib import Path

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict


def _default_root() -> Path:
    return Path(os.environ.get("LLM_API_ROOT", str(Path.home() / "llm-api")))


class Settings(BaseSettings):
    model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8", extra="ignore")

    app_env: str = Field(default="development", alias="APP_ENV")
    domain: str = Field(default="www.llm-api.io", alias="DOMAIN")
    public_url: str = Field(default="https://www.llm-api.io", alias="PUBLIC_URL")

    host: str = Field(default="127.0.0.1", alias="HOST")
    port: int = Field(default=8300, alias="PORT")
    web_url: str = Field(default="http://127.0.0.1:8301", alias="WEB_URL")

    # Storage
    root: Path = Field(default_factory=_default_root, alias="LLM_API_ROOT")
    model_root: Path | None = Field(default=None, alias="MODEL_ROOT")
    data_dir: Path | None = Field(default=None, alias="DATA_DIR")
    log_dir: Path | None = Field(default=None, alias="LOG_DIR")
    database_path: Path | None = Field(default=None, alias="DATABASE_PATH")

    # Memory policy (GB)
    max_model_memory_gb: float = Field(default=45.0, alias="MAX_MODEL_MEMORY_GB")
    absolute_max_memory_gb: float = Field(default=50.0, alias="ABSOLUTE_MAX_MEMORY_GB")
    macos_reserve_gb: float = Field(default=8.0, alias="MACOS_RESERVE_GB")
    min_free_disk_gb: float = Field(default=100.0, alias="MIN_FREE_DISK_GB")

    max_simultaneous_models: int = Field(default=1, alias="MAX_SIMULTANEOUS_MODELS")
    model_idle_timeout_minutes: int = Field(default=30, alias="MODEL_IDLE_TIMEOUT_MINUTES")
    small_model_resident_gb: float = Field(default=3.0, alias="SMALL_MODEL_RESIDENT_GB")
    load_timeout_seconds: int = Field(default=900, alias="LOAD_TIMEOUT_SECONDS")
    generation_timeout_seconds: int = Field(default=1800, alias="GENERATION_TIMEOUT_SECONDS")
    preload_model: str = Field(default="none", alias="PRELOAD_MODEL")

    enable_mlx: bool = Field(default=True, alias="ENABLE_MLX")
    enable_gguf: bool = Field(default=True, alias="ENABLE_GGUF")
    allow_downloads: bool = Field(default=True, alias="ALLOW_DOWNLOADS")
    log_prompts: bool = Field(default=False, alias="LOG_PROMPTS")

    default_max_tokens: int = Field(default=2048, alias="DEFAULT_MAX_TOKENS")
    default_context: int = Field(default=16384, alias="DEFAULT_CONTEXT")

    hf_token: str | None = Field(default=None, alias="HF_TOKEN")
    llama_server_bin: str = Field(default="llama-server", alias="LLAMA_SERVER_BIN")
    worker_python: str | None = Field(default=None, alias="WORKER_PYTHON")
    worker_port_start: int = Field(default=8310, alias="WORKER_PORT_START")
    worker_port_end: int = Field(default=8399, alias="WORKER_PORT_END")

    secret_key: str = Field(default="", alias="SECRET_KEY")
    admin_email: str | None = Field(default=None, alias="ADMIN_EMAIL")
    admin_password: str | None = Field(default=None, alias="ADMIN_PASSWORD")
    session_hours: int = Field(default=24 * 14, alias="SESSION_HOURS")
    secure_cookies: bool = Field(default=False, alias="SECURE_COOKIES")

    metrics_interval_seconds: int = Field(default=15, alias="METRICS_INTERVAL_SECONDS")
    metrics_retention_days: int = Field(default=30, alias="METRICS_RETENTION_DAYS")
    max_body_bytes: int = Field(default=20 * 1024 * 1024, alias="MAX_BODY_BYTES")

    # ---- derived paths -------------------------------------------------
    @property
    def models_dir(self) -> Path:
        return (self.model_root or self.root / "models").expanduser()

    @property
    def data_path(self) -> Path:
        return (self.data_dir or self.root / "data").expanduser()

    @property
    def logs_path(self) -> Path:
        return (self.log_dir or self.root / "logs").expanduser()

    @property
    def db_path(self) -> Path:
        return (self.database_path or self.data_path / "llm-api.db").expanduser()

    @property
    def secret(self) -> str:
        if self.secret_key:
            return self.secret_key
        # Persist a generated secret so sessions survive restarts.
        p = self.data_path / ".secret"
        p.parent.mkdir(parents=True, exist_ok=True)
        if p.exists():
            return p.read_text().strip()
        import secrets

        s = secrets.token_hex(32)
        p.write_text(s)
        os.chmod(p, 0o600)
        return s

    def ensure_dirs(self) -> None:
        for d in (
            self.models_dir,
            self.models_dir / "mlx",
            self.models_dir / "gguf",
            self.models_dir / "embeddings",
            self.models_dir / "rerankers",
            self.models_dir / "vision",
            self.models_dir / "manifests",
            self.data_path,
            self.logs_path,
        ):
            d.mkdir(parents=True, exist_ok=True)


@lru_cache
def get_settings() -> Settings:
    return Settings()